This invention relates to a trial instrument assembly for use in a surgical procedure to replace an orthopaedic joint and to a method of preparing a bone to receive an implant component in such a surgical procedure.
The success of an operation to replace an orthopaedic joint with a joint prosthesis depends on factors that include: (i) selection of appropriate joint prosthesis components; and (ii) accurate preparation of the bone so that the selected prosthesis components are properly located relative to one another and to features of the patient's bone structure. These factors can affect the fit of the prosthesis components in the patient's bone. These factors can also affect the articulation of the joint prosthesis after implantation, in particular as to whether the articulation of the implanted joint prosthesis accurately reproduces that of the patient's healthy natural joint or some other sought joint construction.
A surgeon can make use of images of the patient's bones in a pre-operative planning stage to identify appropriate prosthesis components that will be appropriate to match a patient's anatomy. The planning stage can also include identifying details of steps in the preparation of the patient's bone to receive the selected prosthesis components.
It is normal to check the fit of a selected prosthesis component in a cavity in a prepared bone. This can be done using a trial component that has a shape similar to that of the ultimate implant component which is to be implanted.